<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		.father {
			width: 300px;
			height: 300px;
			border:1px solid red;
		}
		.son1,.son2 {
			width: 100px;
			height: 100px;
			background-color: pink;
		}
		.son1 {
			margin-bottom: 50px;
		}
		.son2 {
			background-color: purple;
			margin-top: 100px;
		}
		.over  {
			overflow: hidden;
		}
	</style>
</head>
<body>
	<div class="father">
		<div class="over">  <!--  over隔开，那么son1和son2就不是属于同一个盒子了 -->
			<div class="son1"></div>
		</div>	
		<div class="son2"></div>
	</div>
</body>
</html>